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Cardiology Exam 2 > Anti-Ischemia Drugs > Flashcards

Anti-Ischemia Drugs Flashcards

1
Q

What are the main determinants of oxygen supply to heart?

How are they impaired?

How is this fixed?

A
  • Blood flow
  • O2 carrying capacity of blood

Impaired by…

  • Dec coronary perfusion pressure, inc coronary resistance, inc extrinsic compressive forces
  • emphysema, pneumonia, change in altitude (less O2 supply)
  • anemia or sickle cell (change Hb content)

Fix by…

  • Inc oxygen supply, inc hematocrit
  • Vasodilate coronary arteries
  • Maintain BP to maintain coronary perfusion pressure
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2
Q

What are the main determinants of oxygen demand of heart?

How are these increased?

How is this fixed?

A
  • Inc HR
  • Inc Contractility
  • Inc wall stress (greater P or V)

Increased if…

  • adrenergics/symp NS
  • anything that inc preload (vol) or after load (pressure)

Fix by…

  • Dec HR
  • Dec Ca++ influx
  • Dec preload
  • Dec afterload
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3
Q

Exogenous Nitrates in General (mechanism, types & dose dependence)

A
  • MAO - converted to NO by mitochondrial aldehyde dehydrogenase
  • Depends on dose
    • @ low dose… venous dilation
    • @ high dose … coronary artery dilation
  • Short acting - mucosal (sublingual or oral spray) or transdermal (ointment) —> dir to blood so rapid onset that can be used for angina as needed; can also use prophylactically b/f activities that trigger angina
  • Long acting - oral or sustained release patch
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4
Q

Positive Oxygen Effects of Nitrates

A

Dec coronary resistance, dec R3 b/c less preload, dec preload and after load so less wall tension (less demand)

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5
Q

5 Side Effects of Nitrates

A
  • Nitrate tolerance (less potent over time); help by dosing so that they are nitrate free for 10-12 hrs a day (“”resensitization”)
  • Headache/flushing - usually go away after 2 wks
  • Hypotension - esp if on diuretic (DO NOT USE IF ALSO ON PDE INHIB - like Viagra)
  • Hypoxemia - dilate vessels in hypoxic part of lung instead of oxygenated part of lung
  • Tissue hypoxia if methemoglobinemia (rare)
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6
Q

What are the 2 long-acting nitrates? How do they differ?

A
  • Isosorbide dinitrate - hepatic 1st pass —> isosorbide mononitrate
  • Isosorbide mononitrate - already in active metabolite form so greater bioavailability; FASTER
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7
Q

3 Categories of Beta Blockers

A
  • Cardioselective
  • Intrinsic Sympathomimetics
  • Alpha Receptor Blocking
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8
Q

Cardioselective Beta Blockers

A
  • preferentially block beta 1 (however un-selective @ high doses)
  • Atenolol, bisoprolol, betaxolol, esmolol, metoprolol
  • Positive effects - dec HR and dec contractility so less demand; dec HR also allows more diastolic filling time so more coronary flow, some inc resistance
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9
Q

IAS Beta Blockers

A
  • weak beta agonists that competitively inhibit the strong catecholamines from binding (shield from natural catecholamines)
  • Pindolol, acebutolol, carteolol, penbutolol
  • Do not use if CAD (may inc mortality)
  • Pos effects - slight dec in HR and contractility but may inc after load - not used for CAD
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10
Q

Alpha Receptor Blocking Beta Blockers

A
  • prevent unopposed alpha adrenergic stimulation during beta blockage so no compensatory vasoconstriction
  • Labetolol, carvedilol
  • Best for HTN
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11
Q

5 Side Effects of Beta Blockers

A
  • CNS - esp if lipophilic (fatigue, sleep problems, depression, sexual dysfunction)
  • Conduction abnormalities - dec SA node rate so brady
  • CHF
  • Exacerbate peropheral vascular disease
  • Dec glycogen breakdown (normally sympathetic beta) so exacerbate DN hypoglycemia
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12
Q

Hydrophilic v. Lipophilic Beta Blockers

A
  • Lipophilic = liver metabolism so shorter half-life & cross BBB so CNS side effects
  • Hydrophilic = renal metabolism so longer half-life & do NOT cross BBB so less CNS effects
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13
Q

2 Categories of Ca Channel Blockers

A
  • Dihydropyridines - more potent vasodilators
  • Non - Dihydro (Benzothiazapines & Phenylalkylamines) - more potent effects on slowing SA and AV node - dec HR and conduction
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14
Q

Dihydropyridines

A
  • Positive effects - dec coronary vascular resistance and dec R3 thru dilation, dec after load and preload by peripheral dilation so less wall tension
  • Can induce reflex tachycardia
  • Nifedipine, amlodipine, felodipine, nicardipine, isradipine
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15
Q

Non-dihydropyridines

A
  • Positive effects - dec coronary resistance still thru vasodilation and dec HR and contractility so less demand
  • Can result in symptomatic bradycardia or AV block (esp in verapamil so do not use w/ beta blocker for risk of complete block)
  • Diltiazem & verapamil
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16
Q

8 Side Effects of Ca Channel Blockers

A
  • All hepatic metabolism except Diltiazem (40% renal) so many drug-drug interactions
  • Hypotension - esp w/ dihydro
  • Exacerbate CHF - esp w/ non-dihydro
  • Conduction abnormalities (above)
  • Edema - augmented vasodilation
  • GI - dec motility b/c smooth muscles relac
  • Gingival hyperplasia - rare
  • **Cardio mortality risk in short-acting nifedipine b/c potent vasodilation —> rapid compensatory adrenergic tone (in long-acting still use w/ beta blocker just in case)
17
Q

What is the role of Ranolazine?

A
  • MAO- inhibits delayed Na channels (late in AP) and Kr channels in myocardial AP; so dec intracellular Na —> more Na/Ca pump —> dec Ca in cell (less Ca overload - more relaxation)
  • SO it dec wall tension by preventing Ca overload in ischemic myocytes
  • Positive Effects - Dec R3 /dec wall tension (demand)
18
Q

Ranolazine Side Effects

A
  • QT prolongation - b/c inhibits K+; can lead to torsade
  • CYP3a metabolism so inc drug if given w/ other drugs that inhibit CYP3a (anti-fungals, anti-retrovirals and antibiotics) or if liver problems —> inc chance of QT prolongation
  • Can also inc digoxin levels
19
Q

How to Choose Drugs for Chronic Ischemic Heart Disease Pt

A
  • First line - beta blockers WITHOUT ISA (intrinsic sympathetic activity)
  • If angina persists… add in long-acting nitrate w/ appropriate nitrate-free interval
  • Can also prescribe short-acting nitrate for as needed basis (acute episodes or prophylaxis)
  • Use non-dihydro in patients w/ contraindications to beta blockers
  • If refractory symptoms - try tri-drug therapy such as ranolzaine

Cardiology Exam 2 (13 decks)

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